In my living room sits this clock, given to my great-grandfather in 1991 for fifty years of service. As I wind it up every few days, it gives me several important reminders in life.

To be the kind of man he was to others, to give the same effort every day as he did to his work and family and the phrase on the clock itself “Tempus Fugit” – Time Flies (make the most of it!).

This clock keeps great time and a few times over the years, I have made an adjustment to the pendulum to keep it in synch with the rest of the world.

Time in an automation system. or rather time synchronization, is an important detail that can often be overlooked until it is needed.

When a machine goes down and you are comparing alarms between systems to understand why it went down it is extremely frustrating to have time discrepancies between systems.

There are different options to create time synchronization within your ControlLogix system and there are modules that can help you stay synchronized automatically through GPS Antenna.

Here are a couple of examples and descriptions of what modules I am talking about:

TIME Modules

1756HP-TIME/1756-TIME

One way of keeping time is with a third party like Hiprom which makes a 1756HP-TIME module.  You can find documentation for configuration using the below link:

Or use the 1756-TIME module from Rockwell:

TIME Protocols

The above modules obtain their time from a GPS Antenna, and can synchronize with other modules using one of two different protocols:

1588 Precision Time Protocol (aka CIP Sync)

Enables high precision time synchronization over an EtherNet Network or the ControlLogix chassis backplane.

When PTP is selected, both EtherNet and Backplane synchronization are enabled.

NTP Protocol (Network Time Protocol)

Used for time synchronization with personal computers or domain controllers, this is configured with a HSNTP application that can be downloaded at www.ab.com.

The 1756-TIME Module supports NTP Version 3, RFC1305.

Synchronization Along the Backplane

Allen-Bradley 1756-EN2x Modules can use CIP Sync to synchronize with the grand clock Master as well as the ControlLogix Processor by enabling Time Synchronization under Controller Properties, or on the main tab of the Ethernet module's configuration as shown in the following images:

  • Enabling Time Synchronization in Controller Properties

  • Enabling Time Synchronization in Ethernet Module Properties

Conclusion

Hopefully, this introduction to ControlLogix time synchronization will be beneficial to you and show you some of the available options if you are seeking precision time synchronization within or across your control systems.

Again, as listed above, a detailed explanation of this can be found in the Rockwell Publication 1756-um542_-en-p.pdf.

Good Luck in your endeavors ahead in TIME.

Written by Brandon Cooper
Senior Controls Engineer and Freelance Writer

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